lint_cset64.c File Reference

Purpose

The cset64 linter ensures that the given data contains only characters within the GS1 AI encodable character set 64 ("CSET 64").

Remarks

CSET 64 is defined in the GS1 General Specifications table "GS1 AI encodable character set 64 (file-safe / URI-safe base64)".

Functional Description

gs1_lint_cset64()

GS1_SYNTAX_DICTIONARY_API gs1_lint_err_t gs1_lint_cset64	(	const char *const	data,
		size_t	data_len,
		size_t *const	err_pos,
		size_t *const	err_len
	)

Used to validate that an AI component conforms to Z..99 syntax, and has valid padding if provided.

Note: The length of the component is validated by the framework that calls this function.

Parameters

[in]	data	Pointer to the data to be linted. Must not be NULL.
[in]	data_len	Length of the data to be linted.
[out]	err_pos	To facilitate error highlighting, the start position of the bad data is written to this pointer, if not NULL.
[out]	err_len	The length of the bad data is written to this pointer, if not NULL.

Returns

GS1_LINTER_OK if okay.

GS1_LINTER_INVALID_CSET64_CHARACTER if the data contains a non-CSET 64 character.

{
 
        /*
         * CSET 64 characters: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
         *
         */
        static const uint64_t cset64_bitfield[] = {
                0x000000000004ffc0,             // 0-9, "-"
                0x7fffffe17fffffe0,             // A-Z, "_", a-z
                0x0000000000000000,
                0x0000000000000000
        };
 
        size_t pads, len, pos;
 
        assert(data);
 
 
        /*
         * Count padding characters from the end
         *
         */
        for (pads = 0; pads < data_len && data[data_len - pads - 1] == '='; pads++);
        len = data_len - pads;
 
        if (GS1_LINTER_UNLIKELY(pads > 2 || (pads > 0 && data_len % 3 != 0)))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_INVALID_CSET64_PADDING,
                        len,
                        pads
                );
 
        /*
         * Validate character set using bitfield lookup
         *
         */
        for (pos = 0; pos < len; pos++) {
                int valid;
                GS1_LINTER_BITFIELD_LOOKUP((unsigned char)data[pos], cset64_bitfield, valid);
                if (GS1_LINTER_UNLIKELY(!valid))
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_INVALID_CSET64_CHARACTER,
                                pos,
                                1
                        );
        }
 
        GS1_LINTER_RETURN_OK;
 
}